A method of treating blood withdrawn from patient including: simultaneously withdrawing blood and infusing withdrawn blood from and to the patient by flowing the withdrawn blood through an extracorporeal dialysis circuit including a dialyzer having a semi-permeable dialysis membrane and a dialysate side adjacent the membrane； feeding a dialysate containing 1 to 5 mM total calcium and 2 to 8 mM citrate to the dialysate side of the dialyzer, and introducing an anticoagulation fluid including at least 8 mM citrate into the arterial blood line.
